<!doctype html> 
<html> 
<head> 
    <meta charset="utf-8"> 
    <title></title> 
</head>
<body>

<script type="text/javascript">
	
var a =String('123');
b = a;
b.c = 10;
alert(a.c);
//alert(typeof a);
//var b = Array(1,2,3);
//alert(b);
//alert(Date())

</script>
</body>
</html>